Foxh1对罗非鱼卵子发生和卵巢发育的调控研究

The study of oogenesis is always an important research area, since egg maturation is a prerequisite for the completion of reproduction. Normally, Oogenesis will be influenced by both hormone released from brain-pituitary-gonadal axis (such as steroids) and cytokines and transcription factors in the ovary. As a member of the Forkhead transcription factors, Foxh1 is a very potential candidate gene to mediate egg development by regulating steroid hormones, while the impact of Foxh1 on animal oogenesis and ovary development has not been reported. In particular, our previous studies demonstrated that Foxh1 is highly expressed in tilapia ovary based on both gonadal transcriptome data and ISH analysis. Foxh1 gene deficient tilapia result in number reduction and developmental delay of oocytes, somatic cell proliferation and lower estrogen level in serum. In this study, we will use Foxh1 gene knockout, overexpression and exogeneous hormone rescue tilapia model to determine the possible function of Foxh1 during tilapia oogenesis and ovary development. Furthermore, we will perform transcriptomic and ChipSeq analyses to screen and identify the target genes regulated by Foxh1. Our research will not only help to reveal the molecular mechanisms of steroidgenesis and oogenesis regulated by Foxh1, but also extend the comprehension of regulatory networks in fish oogenesis and ovary development. Moreover, our study will provide a theoretical foundation for the artificial propagation in aquaculture.

卵子发生是完成生殖的先决条件。因此，对卵子发生的分子调控机制研究是生物学研究的热点之一。卵子发生是一个非常复杂的动态过程，受到下丘脑-垂体-性腺轴所释放的激素如类固醇激素和卵巢中的细胞因子和转录因子的影响。Foxh1是转录因子Fox家族的一员，申请人前期的研究表明Foxh1在罗非鱼卵巢发育和卵子发生过程中高表达，其缺失个体的卵母细胞数量减少、发育延迟，体细胞出现增生并且雌激素水平降低，暗示该基因对卵子发生和卵巢发育有重要作用。然而，目前对Foxh1在动物卵子发生和卵巢发育中的功能研究未见报道。本项目拟通过罗非鱼Foxh1基因敲除、转基因过表达和激素回救模型，检测性腺组织学和血清激素水平变化，结合染色质免疫沉淀和转录组测序等手段筛选Foxh1作用的靶基因并加以验证，从而揭示Foxh1对类固醇激素生成、卵子发生和卵巢发育的分子调控机制。本项目的实施有助于加深人们对鱼类卵子发生调控网络的认识，进而为鱼类人工繁殖提供理论依据。

卵子发生是完成生殖的先决条件。因此，对卵子发生的分子调控机制研究是生物学研究热点之一。卵子发生是一个非常复杂的动态过程，受到下丘脑-垂体-性腺轴所释放的激素如类固醇激素和卵巢中的细胞因子和转录因子的影响。foxh1是转录因子Fox家族的一员，本项目在罗非鱼中建立了foxh1基因纯合敲除模型, 发现90 dah（days after hatching）时，和对照XX鱼一样，foxh1-/-鱼卵巢充满I、II时相卵母细胞。180 dah时，对照鱼卵巢中出现被颗粒细胞和鞘膜细胞包围的III、IV时相卵母细胞。然而，foxh1-/- XX鱼卵巢发育不良，其卵母细胞的发育停滞在I和II时相，仅被单层的前颗粒细胞包围，雌激素水平和GSI显著低于foxh1+/+鱼，卵母细胞发育停滞最终导致雌性不育。转录组测序结果表明，foxh1突变影响foxl2、dmrt1、cyp19a1a和cyp11b2等与卵巢分化相关基因的表达。foxh1突变XX鱼卵巢发育停滞可以被E2处理回救产生双层滤泡细胞，出现III、IV时相卵母细胞。本研究初步揭示了foxh1对类固醇激素生成和卵子发生的分子调控机制，为阐明foxh1在鱼类卵子发生过程中的功能奠定了基础。项目执行期间发表SCI论文3篇。参加国际学术会议5人次，参加国内学术会议4人次。获重庆市自然科学奖三等奖。培养博士生2人，硕士研究生3人。